1. Field of the Invention
This invention relates to resistive-capacitive oscillators and, more particularly, to integrated RC oscillators for generating high frequency oscillations with 0.5 percent stable frequency characteristics.
2. Description of the Prior Art
In many applications such as, for example, the driving oscillator in DC-to-DC converter circuits, it is desirable to generate relatively high oscillation frequencies in order to reduce the size of transformers used in such systems. For applications as subscriber loop carrier systems in which cost, size and power consumption of the converter are of particular importance, it is also desirable to fabricate such oscillators in integrated circuit form. Present technology, however, dictates that integrated oscillators be of the resistance-capacitance type since inductive elements cannot be fabricated in integrated form.
A significant problem with integrated RC oscillators is the tendency of the frequency to drift with changes in temperature of a change in the supply voltages. In applications such as subscriber loop carrier systems where the oscillator frequency might generate frequency components which interface with signal frequencies, such frequency shifts cannot be tolerated.